Keira Knightley faced with adulthood in 'Laggies'

PARK CITY, Utah—Director Lynn Shelton has a great idea for how to market her new film, "Laggies": put video of Keira Knightley dancing as a sign-spinner on YouTube.

Knightley demonstrates some sweet moves and deft sign-spinning skills in one of the opening scenes of the film, which premiered Friday at the Sundance Film Festival.

The actress plays Megan, a 28-year-old who feels directionless despite her graduate degree and stable, 12-year relationship. While her friends pursue careers, marriages and babies, Megan stands in front of her dad's tax office, dancing around with a sign that says "tax advice" in an attempt to drum up business.

"It makes me happy every time I see it," Shelton said, adding that she's sure video of Knightley's routine would "go viral" online.

When Megan's boyfriend proposes, she panics. She befriends a teenage girl (Chloe Grace Moretz) and hides out at her house, where she's intrigued by the girl's single dad (Sam Rockwell).

Shelton, who has had three previous films at Sundance, said the cast was a dream. She said she called the best possible people for the role, and when they all said yes, it was "freaking awesome."

Knightley joked that the three stars had no chemistry.

"We all hated each other," she said. "So it was really, really good acting."